When a speech or music signal is transmitted in a packet communication system typified by Internet communication, a mobile communication system, or the like, compression and encoding technologies are often used in order to increase the transmission efficiency of the speech or music signal. In recent years, while a speech or music signal is simply encoded at a low bit rate, there has been a growing need for a technology that encodes a wider-band speech or music signal.
In response to such a need, various technologies have been developed that encode a wideband speech or music signal without greatly increasing the amount of information after encoding. For example, Patent Literature 1 discloses a technology whereby a characteristic of a frequency high-band part among spectral data obtained by converting an input audio signal of a fixed time is generated as auxiliary information, and this is output together with low-band part coded information.